EP0625732B1 - Méthode et appareil de formation d'images en couleur - Google Patents

Méthode et appareil de formation d'images en couleur Download PDF

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Publication number
EP0625732B1
EP0625732B1 EP94109201A EP94109201A EP0625732B1 EP 0625732 B1 EP0625732 B1 EP 0625732B1 EP 94109201 A EP94109201 A EP 94109201A EP 94109201 A EP94109201 A EP 94109201A EP 0625732 B1 EP0625732 B1 EP 0625732B1
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EP
European Patent Office
Prior art keywords
toner
image bearing
toner image
bearing film
color
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP94109201A
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German (de)
English (en)
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EP0625732A1 (fr
Inventor
Shinichi C/O Oki Electr. Ind. Co. Ltd. Itoh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Oki Electric Industry Co Ltd
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Oki Electric Industry Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP1016309A external-priority patent/JP2548792B2/ja
Priority claimed from JP1016310A external-priority patent/JP2548793B2/ja
Priority claimed from JP1016312A external-priority patent/JPH087483B2/ja
Priority claimed from JP1016311A external-priority patent/JPH0812501B2/ja
Application filed by Oki Electric Industry Co Ltd filed Critical Oki Electric Industry Co Ltd
Publication of EP0625732A1 publication Critical patent/EP0625732A1/fr
Application granted granted Critical
Publication of EP0625732B1 publication Critical patent/EP0625732B1/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0105—Details of unit
    • G03G15/0131—Details of unit for transferring a pattern to a second base
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • G03G15/0157—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member with special treatment between monocolour image formation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • G03G15/0163—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member primary transfer to the final recording medium

Definitions

  • This invention concerns a method and apparatus for forming color images by means of electrophotography according to US-A-3,937,572.
  • a photosensitive drum and a transfer drum carrying recording paper are made to rotate together a plurality of times, and images on the photosensitive drum are transferred the same number of times onto the recording paper on the outer surface of the transfer drum so as to overlay each other.
  • Fig. 1 is a simplified drawing of a color electrophotographic copier employing the conventional color image-forming method (as shown for example in Japanese Patent Application Publication No. 54-19750; and Proceedings of the Inst. of Electrostatics Japan, Vol. 9, No. 4. pp. 253-261, 1985).
  • the surface of a photosensitive drum 1 which rotates at a fixed speed in the counterclockwise direction is electrostatically charged with a specified polarity by a corona discharge device 2.
  • this developing device 4 comprises at least three devices, namely a device for developing yellow images 5, a device for developing magenta images 6, and a device for developing cyan images 7.
  • the exposure device 3 is therefore provided with blue, green and red color separation filters.
  • the developing device 4 may also be provided with a device for black development in order to adjust the color tone if necessary.
  • Developing is performed for each color separately. First, when a color image of the original is projected on the photosensitive body using the blue filter, an electrostatic latent image consisting of yellow element which is the complementary color to blue is formed thereon. This is then rendered visible by the yellow developing device 5.
  • the yellow developing device 5 contains a developing agent of a yellow toner and an iron powder carrier. These two components are mixed together by stirring, and the toner is triboelectrified with a polarity opposite to that of the charge on the electrostatic latent image. Both the toner and carrier are attached onto the developing roller 5a, and are transported to the developing area which is near the photosensitive drum 1.
  • the green and red color separation filters are selected, the magenta and cyan toners are developed, and the toner images are copied onto a recording paper 9 via a transfer drum 8 to form color images on the paper.
  • the outer circumference of the transfer drum 8 must be arranged to be longer than the length of the recording paper 9.
  • the largest size of the recording paper 9 which can be recorded is B4 (JIS Standard)
  • its dimension in the longer direction is 364 mm.
  • the outer diameter of the transfer drum 8 must be not less than 116 mm.
  • the transfer drum 8 Because a mechanism required to hold the recording paper 9 at a fixed point must also be provided on the circumference thereof, the transfer drum 8 must have larger dimensions than the above, and the color copier becomes bulky.
  • This invention aims to eliminate need for the transfer drum and the mechanism to load the recording paper on the photosensitive member, form a recorded image on the paper and release the paper, as well as to reduce the frequency of paper jamming.
  • This invention also aims to facilitate the back and forth transport of the recording paper after transfer and fixing, by having toner images transferred to and fixed on the recording paper by means of thermal energy, thereby enabling a roller to be pressed against the recording paper to which the toner images have been transferred.
  • This invention also aims to eliminate need for separate filters and means for selectively using them, through the use of a toner image bearing film having the functions of the color filters, so that the cost of the color image copier and the area which it occupies can be reduced.
  • a toner image bearing film is passed around a photosensitive member, which is uniformly charged, and exposed successively to a light image corresponding to a first color thereby to form an electrostatic latent image of said first color, to a light image corresponding to a second color thereby to form an electrostatic latent image of said second color, and to a light image corresponding to a third color thereby to form an electrostatic latent image of said third color.
  • Developing devices for said first, second and third colors are provided to face the photosensitive member through the toner image bearing film, so that toner images of said first, second and third colors are developed on the toner image bearing film when it is passing around said photosensitive member.
  • the toner image bearing film is moved past a transfer section, where the toner images are transferred to a recording paper, which is moved in time with the the toner image bearing film.
  • the transfer device may comprise a first roller and a second roller juxtaposed with each other.
  • one of the first and second rollers is a heating roller and the other is a pressure roller, so that they also serve as a fixing means.
  • the pressure roller is separated from the heating roller when the toner image bearing film bearing the toner images of the respective color passes between the heating roller and the pressure roller until the toner images of all the colors have been formed, toner images of a plurality of colors are successively formed, being superimposed with each other, and temporarily fixed on the toner image bearing film by the heat of the heating roller, and the feeding means feeds the recording paper when the toner images of all the colors have been formed on the toner image bearing film. In this way, the toner images of all the colors are simultaneously transferred to and fixed on the recording paper.
  • the first roller is a pressure roller and the second roller is a heating roller
  • the heating roller is kept pressed against the pressure roller when the toner image bearing film bearing the toner image of each color passes between the heating roller and the pressure roller
  • toner images of a plurality of colors are successively formed, being superimposed with each other, and temporarily fixed on the toner image bearing film
  • the feeding means feeds the recording paper when the toner images of all the colors have been formed on the toner image bearing film. In this way, the toner images of a plurality of colors constituting the color image are simultaneously transferred to and fixed on the recording paper.
  • Fig. 1 is a schematic drawing showing a color electrophotographic copier employing the conventional color image-forming method.
  • Fig. 2 is a schematic drawing of the color image-forming apparatus of Embodiment 1.
  • Fig. 3 is a drawing showing the state during the transfer and fixing step according to Embodiments 1 and 2.
  • Fig. 4 is a drawing showing the state when the recording paper has returned according to Embodiments 1 and 2.
  • Figs. 5A to 5D are drawings showing the electrifying step, the exposure step, the developing step, and the transfer and fixing step that occur in the case of yellow toner.
  • Figs. 6A to 6D are drawings showing the electrifying step, the exposure step, the developing step, and the transfer and fixing step that occur in the case of magenta toner.
  • Figs. 7A to 7D are drawings showing the electrifying step, the exposure step, the developing step, and the transfer and fixing step that occur in the case of cyan toner.
  • Fig. 8 is a schematic drawing of the color image-forming apparatus of Embodiment 2.
  • Figs. 9A to 9D are drawings showing the electrifying step, the exposure step, the developing step, and the transfer and fixing step that occur in the case of yellow toner.
  • Figs. 10A to 10D are drawings the electrifying step, the exposure step, the developing step, and the transfer and fixing step that occur in the case of magenta toner.
  • Figs. 11A to 11D are drawings showing the electrifying step, the exposure step, the developing step, and the fourth transfer and fixing step that occur in the case of cyan toner.
  • Fig. 12 is a schematic drawing of the color image-forming apparatus of Embodiment 3.
  • Fig. 13 is a drawing showing the state when color images are formed.
  • Fig. 14 is a drawing showing the state during the transfer and fixing step.
  • Figs. 15A to 15D show the electrifying step, the exposure step, the developing step, and the deposition step that occur in the case of cyan toner.
  • Figs. 16A to 16D show the electrifying step, the exposure step, the developing step, and the deposition step that occur in the case of magenta toner.
  • Figs. 17A to 17C show the electrifying step, the exposure step and the developing step that occur in the case of yellow toner.
  • Fig. 18 shows the transfer and fixing step that occur in the case of yellow toner.
  • Fig. 19 is a schematic drawing of the color image-forming apparatus of Embodiment 4.
  • Figs. 20A to 20D show the electrifying step, the exposure step, the developing step, and the deposition step that occur in the case of cyan toner.
  • Figs. 21A to 21D show the electrifying step, the exposure step, the developing step, and the deposition step that occur in the case of magenta toner.
  • Figs. 22A and 22C show the electrifying step, the exposure step, the developing step, that occur in the case of yellow toner.
  • Fig. 23 shows the transfer and fixing step that occur in the case of yellow toner.
  • Fig. 2 is a schematic drawing of the color image-forming apparatus according to the invention.
  • the illustrated color image forming apparatus comprises a photosensitive drum 11 rotatably mounted on a frame, not shown.
  • the photosensitive drum 11 may be one having a selenium photosensitive body comprising a photosensitive layer on an electrically conducting support, a negatively charged organic photosensitive body, or a positively charged organic photosensitive body.
  • the color image forming apparatus also comprises a transfer and fixing section 45 formed of a heating roller 12 and a pressure roller 13 which are juxtaposed with each other.
  • the heating roller 12 may be of a hollow metal member enclosing a halogen lamp, or one having a heat-emitting body on a metal surface.
  • the surface of the pressure roller 13 is covered with silicone rubber in order to provide heat stability.
  • An endless toner image bearing belt or film 14 is passed around the photosensitive drum 11 and moves past the transfer and fixing section 45. More particularly, the toner image bearing film 14 is in contact, on a first or inner surface thereof, with the peripheral surface of the photosensitive drum 11 over a portion of the photosensitive drum arc, and as the photosensitive drum 11 rotates, the toner image bearing film 14 moves together with the photosensitive drum 11. Where the toner image bearing film 14 moves past the transfer and fixing section 45 it passes around the heating roller 12 and between the heating roller 12 and the pressure roller 13.
  • the pressure roller 13 can selectively assume one of the two positions: a contact position in which it is pressed against the heating roller 12 clamping the toner image bearing film 14, and a release position in which It separated from the heating roller 12.
  • the pressure roller 13 is moved between the two positions by a means to be described later with reference to Fig. 3 and Fig. 4.
  • the elasticity of the silicone rubber layer of the pressure roller 13, the diameter for the pressure roller 13, and the pressing force applied between the pressure roller 13 and the heating roller 12 are so designed as to provide a just enough nip width.
  • a charging or electrifying device 15 As the photosensitive drum 11 rotates its surface sequentially passes various processing sections or devices, namely, a charging or electrifying device 15, an exposure device 16, developing devices 17, 19 and 21, and a discharge lamp 25.
  • some of the processing devices i.e., the exposure device 16, and the developing devices 17, 19 and 21, are provided to face the photosensitive drum, not directly, but through the toner image bearing film 14.
  • the toner image bearing film 14 is brought into contact with the photosensitive drum 14.
  • the toner image bearing film 14 is separated from the photosensitive drum 11.
  • the electrifying device 15 is a corona discharge device for providing an electrostatic charge uniformly over the photosensitive surface of the photosensitive drum 11.
  • the electrifying device 15 may alternatively be formed of a brush discharge device.
  • the exposure device 16 exposes the photosensitive drum 11 through the toner image bearing film 14 to a light image or radiation pattern to form an electrostatic latent image on the photosensitive surface of the photosensitive drum 11.
  • the areas which have been irradiated by light are discharged, while the areas or dots of the photosensitive drum which have not been irradiated are kept charged, so the latent image consists of charged areas and discharged areas.
  • This does not mean that each area assumes either of the two distinct state, the charged and the discharged: there can be intermediate state and the degree to which each area is discharged depends on the density of the respective areas of the image.
  • the exposure is repeated the same number of times as the number of the colors of the toners with which the color image is formed.
  • toners of the three primary colors, yellow, magenta and cyan are used, so the exposure is repeated three times, and the light pattern at each exposure is for the image of each color component.
  • the toner image bearing film 14 must therefore be transparent to the wavelengths of the light used for the exposure.
  • the exposure device 16 may be a combination of a light source such as a laser or an LED array and an optical imaging system, and in this case, the light pattern for each color is produced by electrical signals representing the image of each color. Such electrical signals are supplied from a controller 50 which performs the overall control of the apparatus.
  • the exposure device 16 may alternatively be a combination of an illuminating device illuminating an original document and an optical system for directing the light reflected at the surface of the original to the photosensitive surface of the drum 11 through filters of colors complementary to the colors of the toners. In such a case, the selective placement or insertion of the filters are made by means not shown under control of the controller 50.
  • the developing devices 17, 19 and 21 are the ones for applying toners of yellow (Y), magenta (M) and cyan (C). These developing devices 17, 19 and 21 are installed facing the outer surface of the toner image bearing film 14 which moves in close contact with the photosensitive drum 11, as described above. They are respectively provided with developing agent supports 17a, 19a and 21a for yellow (Y), magenta (M) and cyan (C) toners 18, 20 and 22 being attached on the supports and transported so as to develop the toner images on the outer surface of the toner image bearing film 14.
  • the developing devices may be a binary (two-component) magnetic brush developer, a unitary (one-component) magnetic brush developer, or a unitary non-magnetic brush developer.
  • the developing devices 17, 19 and 21 are successively activated by the controller 50 in accordance with the color of the latent image which has just been formed by the exposure device 16.
  • the discharge lamp 25 is provided so as to face the part of the photosensitive drum 11 which has just separated from the toner image bearing film 14 after developing.
  • the function of the discharge lamp 25 is to irradiate the entire photosensitive drum to dissipate all the charges on it thereby making it ready for next operation.
  • the toner image bearing film 14 passes around the photosensitive drum 11, and the transfer and fixing section 45.
  • the toner image bearing film 14 also passes a fixing cleaner 23 and then a discharge brush 24.
  • the cleaner 23 is provided in apposition to the heating roller 12, but after the transfer and fixing section 45.
  • the function of the cleaner 23 is to remove any residual toner from the toner image bearing film 14 after transfer of the toner image to a recording paper 27 to be described later.
  • the discharge brush 24 is provided in contact with the toner image bearing film 14. The function of the discharge brush 24 is to remove any residual electrostatic charge from the toner image bearing film 14.
  • Pinch rollers 26a and 26b are disposed being pressed against the pressure roller 13, on both sides of transfer and fixing section 45, such that the recording paper 27 is wound on the pressure roller 13 over a sufficient portion of the pressure roller arc.
  • the paper feed system for the recording paper 27 is comprised of a paper feed cassette 40, a paper pick-up roller 41, a paper advance roller 42 and a paper eject roller 43. Their operation, i.e., forward and backward rotation are controlled by the controller 50.
  • a frame 28 supporting the heating roller 12 and a frame 29 supporting the pressure roller 13 are supported such that they can rotate freely on a pivot 30.
  • the pressure roller 13 is pressed against the heating roller 12 by the tensile force of a spring 31 attached to the frames 28 and 29.
  • a solenoid 32 serves to apply a back-and-forth motion to a shaft 33, and causes the frame 29 to rotate, such that the pressure roller 13 is pressed against or separated from the heating roller 12.
  • the transfer and fixing process is carried out with a recording paper 27 being passed between the pressure roller 13 and the toner image bearing film 14 on the heating roller 12.
  • the recording paper 27 may be moved backward, e.g., after transfer of toner image of one color and to be ready for transfer of toner image of another color.
  • the excitation and de-excitation of the solenoid 32 is controlled by the controller 50.
  • any other actuator may be used to selectively move the pressure roller 13 between the two positions.
  • the photosensitive drum 11 and the heating roller 12 are rotated at a constant peripheral speed in the directions shown by the arrow in the figure by a drive mechanism not shown. As a result, due to the friction with the photosensitive drum 11 and the heating roller 12, the toner image bearing film 14 is moved in the direction shown by the arrow.
  • the surface of the photosensitive drum 11 is directly charged uniformly by the corona discharge device 15.
  • the figure shows the case where a selenium photosensitive body is used. In this case, when a high voltage is applied to the corona discharge device 15, the surface is charged positively.
  • a light image corresponding to the yellow image signal produced by the exposure device 16 irradiates the photosensitive layer lla of the photosensitive drum 11 to form an electrostatic latent image for the yellow component of the color image.
  • a means 132 of applying a bias potential is connected across the electrically conducting support 11b of photosensitive drum 11 and the toner support 17a, to apply a bias potential.
  • the discharged areas of the latent image on the photosensitive drum 11 attract the positively charged yellow toner 18, and the attracted yellow toner 18 is attached to the outer surface of the toner image bearing film 14 directly over the discharged areas.
  • electric lines of force are generated between the developer support 17a and the discharged areas of the latent image on the photosensitive drum 11, and toner image bearing film 14, passing through the toner image bearing film 14.
  • the particles of the yellow toner 18 travel along these electric lines of force and adhere to the outer surface of the toner image bearing film 14, and are kept adhering there by a relatively weak electrostatic force.
  • the toner image on the toner image bearing film 14 is moved past the transfer and fixing section 45 where the transfer and fixing step shown in Fig. 5D takes place.
  • the recording paper 27 is fed to the transfer and fixing section 45. More specifically, the recording paper is supplied from a paper supply cassette 40, being picked up by a pick-up roller 41, and is advanced by the paper advance roller 42, in synchronization with the toner images on the toner image bearing film 14, such that the leading edge of the recording paper (to be precise, the leading edge of the area in which the color image is to be reproduced) comes into contact with the leading edge of the area of the toner image bearing film 14 in which the toner image is formed.
  • the toner image bearing film 14 and the recording paper 27 are moved at the same speed.
  • the recording paper 27 and the toner image bearing film 14 are held between the pressure roller 13 and the heating roller 12.
  • the yellow toner image on the toner Image bearing film 14 is therefore melted by the heat of the heating roller 13, whereupon the pressure causes melted toner 18 to permeate the fibers of the recording paper 27. This transfers and fixes the toner images so as to form a yellow image on the recording paper 27.
  • a small amount of yellow toner 18 may remain on the toner image bearing film 14, however this will be wiped off by the cleaner 23 which is brought into contact with the heating roller 12. Further, a discharge brush 24 removes any residual static electricity from the toner image. In this way, the toner image bearing film 14 is cleaned and electrically discharged, and may thus be used again.
  • the photosensitive drum 11 separates from the toner image bearing film 14, and is irradiated by a discharge lamp 25 so as to dissipate any residual electrostatic charge on the photosensitive drum. The drum then returns to the electrifying step, and may thus be used again.
  • an image of magenta toner 20 is developed on the paper via an electrifying step (Fig. 6A), an exposure step corresponding to the magenta image signal (Fig. 6B), a developing step (Fig. 6C) and a transfer and fixing step (Fig. 6D).
  • an image of cyan toner is transferred and fixed via an electrifying step (Fig. 7A), an exposure step (Fig. 7B), a developing step (Fig. 7C), and a transfer and fixing step (Fig. 7D).
  • toner images of the respective colors are transferred to and fixed on the recording paper 27 successively.
  • the pressure roller 13 is pressed against the heating roller 12, and the recording paper 27 is fed in synchronism with the toner image bearing film 14.
  • the pressure roller 13 is separated from the heating roller 12, and the recording paper 27 is moved backward.
  • black toner may also be used.
  • the toner image bearing film 14 is heated by the heating roller 13 to reach a temperature of about 160°C. It must therefore be heat resistant, must have insulating properties to a certain extent, and must also be transparent to the source light wavelengths used in the exposure step. From these considerations, the toner image bearing film used may be formed of a material such as polyester, polyimide, polyetherimide, polyethersulfone or polyetheretherketone.
  • a film of Teflon (Trademark, Polytetrafluoroethylene)-coated polyimide is used.
  • the transfer efficiency is then approximately 100%, there is less load on the cleaner 23, and the life of the cleaner 23 can be extended.
  • the thickness of the toner image bearing film 14 be no greater than 200 ⁇ m; while from considerations of tensile strength and ease of handling, it is desirable that its thickness be not less than 10 ⁇ m.
  • thermal-fixing toners are used for toners 18, 20 and 22.
  • Microcapsule pressure-fixing toners which can be fixed by applying a minute pressure, may also be used.
  • a toner image bearing film transparent to the light source wavelengths is used, and the exposure is made through the toner image bearing film which moves in close contact with the photosensitive drum. It is however also possible to expose the photosensitive drum directly, and bring the toner image bearing film in contact with the photosensitive drum after the exposure step. In this case, there is no need for the toner image bearing film to be transparent to the light source wavelengths.
  • a photosensitive film can be used in place of photosensitive drum 11.
  • Fig. 8 is a schematic drawing of the color image-forming apparatus of this embodiment.
  • a toner image bearing film 14 is passed around the photosensitive drum 11, and the heating roller 12, as in Embodiment 1, and in addition, around free rollers 135a and 135b.
  • the surface of the toner image bearing film 14 is successively coated to constitute a blue filter part 114a, a green filter part 114b and a red filter part 114c, functioning as blue, green and red filters.
  • filter parts of the complementary colors i.e., the blue filter part 114a, the green filter part 114b and the red filter part 114c are used for the exposure.
  • a glass plate 116a is installed above the area where the toner image bearing film 14 is in close contact with the photosensitive drum 11, and a white light source 116b is disposed to irradiate the original 116b laid on the glass plate 116a.
  • the light reflected from the original 116b is then made to form an image on the photosensitive drum 11 by an optical imaging device 116d.
  • the image formed by the optical imaging device 116d at any moment is a representation of an image of a linear area of the original, and as the glass plate 116a is moved, this linear area is shifted along the direction of the movement. Thus, the original 116d is effectively scanned.
  • the glass plate 116a is moved at a constant speed in the direction as indicated by the arrow.
  • the photosensitive drum 11, the heating roller 12 and the pressure roller 13 are rotated in the directions shown by the arrow at a constant peripheral speed, so that the toner image bearing film 14 is moved by friction with the photosensitive drum 11 and the heating roller 12.
  • the rotation of the photosensitive drum 11 and the movement of the toner image bearing film 14 are synchronized with the movement of the glass plate 116a. More specifically, the movement of the toner image bearing film 14 is so timed that when the leading edge of any of the filter parts 114a, 114b and 114c moves past the exposure device, the scanning of the original is started.
  • the movement of the toner image bearing film 14 and the operation of the developing devices 17, 19 and 21 are also so related that the yellow developing device 17 is activated when the blue filter parts 114a is moving past it, the magenta developing device 19 is activated when the green filter parts 114b is moving past it, and the cyan developing device 21 is activated when the red filter parts 114c is moving past it.
  • the necessary control for these timed operations is made by a controller similar to the controller 50 shown in Fig. 2.
  • the surface of the photosensitive drum 11 is directly charged uniformly by the corona discharge device 15.
  • yellow toner 18 charged on the developer support 17a adheres to the blue filter part 114a of the toner image bearing film 14.
  • the recording paper 27, which is supplied and advanced from the supply cassette 40 in synchronization with the yellow toner image on the toner image bearing film 14 is passed around the pressure roller 13.
  • the pressure roller 13 is pressed against the heating roller 12 to hold the toner image bearing film 14 and the recording paper 27 between it and the heating roller 12.
  • the yellow toner 18 adhering to the blue filter part 114a of the toner image bearing film 14 is then melted by the heat of the heating roller 12, and is caused by pressure to permeate the fibers of the recording paper 27. In this way, the yellow toner image is transferred to and fixed on the recording paper 27.
  • the pressure roller 13 When the image produced by the yellow toner 18 has been transferred and fixed up to the trailing edge of the image, the pressure roller 13 is separated from the heating roller 12. The pressure roller 13 is then rotated in the reverse direction, the recording paper 27 returns so as to be ready for the transfer and fixing process of the next color toner.
  • the glass plate 116a is also moved in the reverse direction so as to return to its original position.
  • a magenta toner image is transferred and fixed via an electrifying step, an exposure step, a developing step, and a transfer and fixing step, as shown in Figs. 10A to 10D.
  • reflected light passes through the green filter part 114b of the toner image bearing film 14.
  • the leading edge of the green filter part 114b is made to pass the exposure device 16 when the second scanning of the original 116b is started.
  • the green light G thus color-separated falls on the photosensitive drum 11, and forms an electrostatic latent image.
  • magenta toner 20 on the developer support 19a adheres to the green filter part 114b of the toner image bearing film 14.
  • an image of cyan toner is transferred and fixed via a electrifying step, a exposure step, a developing step and a transfer and fixing step, as shown in Figs. 11A to 11D.
  • an image of cyan toner 22 is transferred and fixed over the image of yellow toner 18 and the image of magenta toner 22 which have been transferred to and fixed on the recording paper 27, thereby forming a color image.
  • the toner images on the filter parts are successively transferred to and fixed on the recording paper 27 while the pressure roller 13 is pressed against the heating roller 12.
  • the pressure roller 13 is separated from the heating roller 12, and the recording paper 27 is moved backward.
  • Embodiment 2 can be modified in the same manner as described with reference to Embodiment 1.
  • Fig. 12 is a schematic drawing of the color image-forming apparatus of this embodiment.
  • a color image consisting of superimposed toner images of three colors is first formed on the toner image bearing film 14, and then this color image is transferred onto a recording paper 27.
  • This is achieved by controlling the exposure to take place in time with the movement of the toner image bearing film 14. More specifically, commencement of exposure for an image of each color must be controlled to take place such that the leading edge of the area for the toner image on the toner image bearing film 13 is brought into contact with the leading edge of the area of the latent image on the photosensitive drum 11.
  • This control is also performed by a controller similar to the controller 50 shown in Fig. 2, with the aid of means of detecting the position of the leading edge of the area for the toner image on the toner image bearing film 14.
  • the toner image of each color on the toner image bearing film 14 is temporarily fixed before the toner image of another color is developed on it so that the toners formed on the toner image bearing film will not be mixed with the toner of the different color inside the developing device.
  • the heating roller 12 heats the toner image bearing film 14 while the pressure roller 13 and a fixing cleaner 223 are kept separated from the heating roller 12.
  • the pressure roller 13 and the cleaner 27 are pressed against the heating roller 12, and the recording paper 27 is fed between the pressure roller 13 and the toner image bearing film 14 on the heating roller 12.
  • the toner image bearing film 14 is passed around the photosensitive drum 11, and the heating roller 12, and, additionally a free roller 235.
  • the exposure device 16 is provided to face the photosensitive drum 11 directly, i.e., without the toner image bearing film 14 interposed.
  • the free roller 235 is provided so that the portion of the photosensitive drum arc which is not covered by the toner image bearing film 14 is long enough to permit the exposure device to be disposed facing the photosensitive drum 11, i.e., inside the space defined by the inner surface of the toner image bearing film 14, and the uncovered part of the photosensitive drum 11, as well as to ensure that the toner image bearing film 14 has a sufficient length for complete toner image to be formed on it.
  • the cleaner 223 is provided facing the toner image bearing film 14 passing round the heating roller 12.
  • the cleaner 223 can selectively assume a contact position in which it is in pressure-contact with the toner image bearing film 14 and a release position in which it is separated from the toner image bearing film 14.
  • Fig. 13 and Fig. 14 show a mechanism for moving the pressure roller 13 and the cleaner 223 between two positions.
  • Fig. 13 shows the state in the release position
  • Fig. 14 shows the state in the contact position.
  • the mechanism shown in these figures is similar to that shown in Fig. 3 and Fig. 4, except that the cleaner 223 is also mounted on the frame 29 and moves with the pressure roller 13.
  • the photosensitive drum 11 and the heating roller 13 are rotated at a constant peripheral speed in the direction shown by the arrow.
  • the toner image bearing film 14 is moved in the direction shown by the arrow.
  • the surface of the photosensitive drum 11 is directly charged uniformly by the corona discharge device 15.
  • the toner image formed on the toner image bearing film 14 adheres to the toner image bearing film 14 by a weak electrostatic force.
  • the toner image bearing film 14 upon which the image of cyan toner 22 is formed arrives at the part of the heating roller 12 and the cyan toner 22 is melted by the heat of the heating roller 12. Due to this heating, the cyan toner 22 adheres to the toner image bearing film 14 with a stronger force than an electrostatic force, in other words, the cyan toner image is temporarily fixed on the toner image bearing film 14.
  • an image of magenta toner 20 is developed on the toner image bearing film 14 upon which the image of cyan toner 22 has been formed, via an electrifying step (Fig. 16A), an exposure step (Fig. 16B), and a developing step (Fig. 16C).
  • the image of magenta toner 20 is exactly superimposed with the image of cyan toner 22, by the control of the controller 50, as described above.
  • the controller 50 controls the cyan toner 22 toner 22 toner image bearing film 14.
  • the pressure roller 13 and the cleaner 223 are brought into pressure-contact with the heating roller 12.
  • the recording paper 27 is supplied by the paper pick-up roller 41, and is advanced by the paper advance roller 42 between the pressure roller 13 and the heating roller 12 in synchronization with the toner images on the toner image bearing film 14.
  • the color image on the toner image bearing film 14 is then melted by the heat of the heating roller 12, whereupon the pressure causes the melted toners 18, 20 and 22 to permeate the fibers of the recording paper 27.
  • a color image is formed on the recording paper 27.
  • the recording paper 27 is then ejected by the ejecting roller 43.
  • toners 18, 20 and 22 may remain on the toner image bearing film 14 after transfer to the recording paper 27, however they will be wiped off by the cleaner 223 which is now also in pressure-contact with the heating roller 12.
  • the pressure roller 13 is separated from the heating roller 12 until all the toner images of all the three colors have been formed on the toner image bearing film 14.
  • Toner images of the three colors are successively formed on the toner image bearing film 14, being superimposed with each other, and temporarily fixed on the toner image bearing film 14 by the heat of the heating roller 12.
  • the pressure roller 13 is pressed against the heating roller 12, and the recording paper 27 is supplied so that the toner images of all the three colors are transferred to and fixed on the recording paper 27 simultaneously.
  • the cleaner 223 for removing any residual toner on the toner image bearing film 14 is activated when the transfer of the toner images of all the three colors has taken place. Before then, it is de-activated and restrained from the cleaning action.
  • the toner 18 which is the last of the color toners 18, 20 and 22 to be developed, is transferred to and fixed on the recording paper 27, directly, i.e., without being temporarily fixed on the toner image bearing film 14. It may alternatively be first temporarily fixed on the toner image bearing film 14 as in the case of the other toners 20 and 22, and subsequently transferred to and fixed on the recording paper 27.
  • Embodiment 3 can be modified in the same manner as described with reference to Embodiments 1 and 2.
  • Fig. 19 is a schematic drawing of the color image-forming apparatus of this embodiment.
  • This embodiment is similar to Embodiment 3, but the position of the pressure roller and the heating roller are exchanged.
  • the pressure roller and the heating roller are renumbered as 312 and 313, respectively, but their structures are similar to the pressure roller 13 and the heating roller 12, respectively.
  • the toner image bearing film 14 is passed around the photosensitive drum 11, the pressure roller 312 and the free roller 235.
  • the heating roller 313 Because of the reversed disposition of the heating roller 313 it must be kept pressed against the pressure roller 312 around which the toner image bearing film 14 is passed. Accordingly, the heating roller 313 is contacted with the images of cyan toner and magenta toner that have been formed on the outer surface of the toner image bearing film 14 when the toner image bearing film 14 is passed through the heating roller 313 for temporary fixing.
  • the surface energy of the heating roller 313 must be less than the surface energy of the toner image bearing film 14, and for this purpose, the metal surface of the heating roller 313 is Teflon coated.
  • a fixing cleaner 323a is provided to face the toner image bearing film 14 on the pressure roller 312.
  • the fixing cleaner 323a can selectively assume a contact position in which it is pressed against the pressure roller 312 and a release position in which it is separated from the pressure roller 312.
  • Another fixing cleaner 323b is provided, being pressed against the heating roller 313.
  • the function of the cleaner 323b is to remove any toner that has been offset to the heating roller 313.
  • a controller similar to the controller 50 shown in Fig. 2 is also provided in this embodiment, but its illustration is omitted.
  • the surface of the photosensitive drum 11 is charged uniformly by the corona discharge device 15.
  • an image of magenta toner 20 is developed, being superimposed, on the toner image bearing film 14 upon which the image of cyan toner 22 has been formed, via an electrifying step (Fig. 21A), an exposure step (Fig. 21B), and a developing step (Fig. 21C).
  • Fig. 21A electrifying step
  • Fig. 21B exposure step
  • Fig. 21C developing step
  • the recording paper 27 is supplied by the paper pick-up roller 41, and is advanced by the paper advance roller 42 between the pressure roller 312 and the heating roller 313, in synchronization with the toner images.
  • the toner images on the toner image bearing film 14 are then melted by the heat of the heating roller 313, caused to permeate the fibers of the recording paper 27 by pressure, transferred to and fixed on the recording paper. As a result, a color image is formed on the recording paper 27.
  • the recording paper 27 is then ejected by the ejecting roller 43.
  • the cleaner 323a While the toner image bearing film 14 is passed around the pressure roller 312 for temporary fixing of the images of cyan toner and magenta toner, the cleaner 323a is kept separated from the pressure roller 312. When the toner image bearing film 14 is passed around the pressure roller 312 for transfer of the color image to the recording paper 27, the cleaner 323a is pressed against the pressure roller 312 to remove any residual toner from the toner image bearing film 14.
  • the cleaner 323a is separated from the pressure roller 312 until the toner images of all the three colors have been formed.
  • Toner images of all the three colors are successively formed on the toner image bearing film 14, being superimposed with each other, with the first and the second being temporarily fixed on the toner image bearing film 14 by the heat of the heating roller 313.
  • the recording paper is supplied and the toner images of all the three colors are simultaneously transferred to and fixed on the recording paper.
  • the cleaner 323a for removing any residual toner on the toner image bearing film 14 is activated when the transfer of the toner images of all the colors has taken place. Until then, the cleaner 323a is deactivated and restrained from the cleaning action.
  • Embodiment 4 can be modified in the same manner as described with reference to Embodiments 1, 2 and 3.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Color Electrophotography (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)

Claims (19)

  1. Procédé pour former des images en couleur, comprenant les étapes consistant à :
    (a) électriser un élément photosensible (11) ;
    (b) exposer l'élément photosensible ;
    (c) développer les images à vireur en collant un vireur sur un film de support d'images à vireur (14) qui se déplace de telle façon qu'une partie de celui-ci soit en contact avec l'élément photosensible (11) ;
    (d) lesdites étape d'électrisation, étape d'exposition et étape de développement sont effectuées pour des vireurs (18, 20, 22) de plusieurs couleurs différentes de manière à former successivement des images à vireur en couleur sur le film de support d'images à vireur (14) ; et
    (e) à transférer les images à vireur à partir du film de support d'images à vireur (14) sur le papier d'enregistrement (27) et à les fixer dessus ; caractérisé en ce que
       les images formées à l'étape (d) sauf celle qui est formée en dernier, ou comportant la dernière, sont fondues sous l'action de la chaleur de manière à les fixer temporairement sur le film de support d'images à vireur ; et par la suite
       toutes les images à vireur sur ledit film de support d'images à vireur sont transférées et fixées sur le papier d'enregistrement.
  2. Procédé pour former des images en couleur selon la revendication 1, dans lequel le film de support d'images à vireur (14) et le papier d'enregistrement (27) passent entre deux rouleaux (12, 13) qui peuvent prendre soit une position de contact par pression, soit une position desserrée, plusieurs images à vireur sont superposées successivement sur le film de support d'images à vireur dans la position desserrée, et toutes les images à vireur en couleur sur le film de support d'images à vireur sont transférées et fixées sur le papier d'enregistrement dans la position de contact par pression.
  3. Procédé pour former des images en couleur selon la revendication 1, dans lequel deux rouleaux (312, 313) serrent le film de support d'images à vireur (14) et le papier d'enregistrement (27) pendant ladite étape de transfert et de fixage.
  4. Procédé pour former des images en couleur selon la revendication 1, dans lequel ledit vireur est un vireur à fixage thermique.
  5. Procédé pour former des images en couleur selon la revendication 1, dans lequel ledit vireur est un vireur à fixage par pression.
  6. Dispositif d'électro-photographie en couleur comprenant :
    un élément photosensible (11) ;
    un dispositif de transfert (12, 13 ; 312, 313) ;
    un film de support d'image à vireur (14) passant autour dudit élément photosensible et passant au niveau dudit dispositif de transfert ;
    un dispositif d'électrisation (15) prévu face audit élément photosensible pour électriser uniformément l'élément photosensible ;
    un dispositif d'exposition (16) pour exposer successivement l'élément photosensible, à une image lumineuse correspondant à une première couleur pour former ainsi une image latente électrostatique de ladite première couleur, à une image lumineuse correspondant à une seconde couleur pour former ainsi une image latente électrostatique de ladite seconde couleur, et à une image lumineuse correspondant à une troisième couleur pour former ainsi une image latente électrostatique de ladite troisième couleur ;
    des dispositifs de développement (17, 19, 21) pour lesdites première, seconde et troisième couleur, pour développer successivement des images à vireur desdites première, seconde et troisième couleurs en faisant adhérer un vireur de ladite première couleur, un vireur de ladite seconde couleur, et un vireur de ladite troisième couleur, sur ledit film de support d'images à vireur (14) lorsqu'il passe autour dudit élément photosensible ;
    un moyen (235) pour faire passer ledit film de support d'images à vireur au niveau desdits dispositifs de développement, et dudit dispositif de transfert ; et
    un moyen (41, 42, 43) pour amener le papier d'enregistrement (27) au niveau dudit dispositif de transfert en synchronisation avec le passage desdites images à vireur sur ledit film de support d'images à vireur au niveau dudit dispositif de transfert ;
    ledit dispositif de transfert transférant lesdites images à vireur desdites première, seconde et troisième couleurs sur le film de support d'images à vireur sur le papier d'enregistrement ;
       caractérisé en ce qu'il comprend de plus
       un moyen (12, 313) pour faire fondre sous l'action de la chaleur les images à vireur sauf celle qui est formée en dernier, ou comportant la dernière, de manière à les fixer temporairement sur le film de support d'images à vireur.
  7. Dispositif selon la revendication 6, dans lequel
       ledit film de support d'images à vireur (14) est un film sans fin passant périodiquement autour dudit élément photosensible et passant au niveau dudit dispositif de transfert.
  8. Dispositif selon la revendication 6, dans lequel
       ledit film de support d'images à vireur (14) est transparent aux longueurs d'onde de la lumière dudit dispositif d'exposition ; et ledit dispositif d'exposition est prévu face audit élément photosensible de l'autre côté dudit film de support d'images à vireur.
  9. Dispositif selon la revendication 6, dans lequel
    ledit dispositif de transfert (12, 13 ; 312, 313) comprend un premier rouleau, et un second rouleau juxtaposé audit premier rouleau,
    ledit film de support d'images à vireur passe autour dudit premier rouleau (12 ; 312) et entre lesdits premier et second rouleaux, et
    ledit moyen d'amenée (41, 42, 43) amène ledit papier d'enregistrement entre le film de support d'images à vireur sur ledit premier rouleau et ledit second rouleau.
  10. Dispositif selon la revendication 9, dans lequel ledit second rouleau (13) peut prendre sélectivement une position de contact dans laquelle il est poussé contre ledit premier rouleau (12) et une position de relâchement dans laquelle il est éloigné dudit premier rouleau.
  11. Dispositif selon la revendication 9, dans lequel un desdits premier et second rouleaux (12, 13 ; 312, 313) est un rouleau chauffant (12 ; 313) et lesdits premier et second rouleaux servent aussi à fixer l'image à vireur sur le papier d'enregistrement (27).
  12. Dispositif selon la revendication 9, dans lequel ledit premier rouleau (12) est un rouleau chauffant (12) et ledit second rouleau (13) est un rouleau de pression (13).
  13. Dispositif selon la revendication 12, comprenant de plus un dispositif de nettoyage (223, 323a) pour enlever tout vireur résiduel sur le film de support d'images à vireur après le transfert de l'image à vireur sur le papier d'enregistrement.
  14. Dispositif selon la revendication 12, dans lequel
    ledit film de support d'images à vireur (14) est un film sans fin ;
    ledit rouleau de pression (13) est éloigné dudit rouleau chauffant lorsque ledit film de support d'images à vireur portant les images à vireur de la couleur respective passe entre ledit rouleau chauffant et ledit rouleau de pression jusqu'à ce que les images à vireur de toutes les couleurs aient été formées ;
    des images à vireur de plusieurs couleurs sont formées successivement, étant superposées les unes aux autres, et fixées temporairement sur ledit film de support d'images à vireur sous l'action de la chaleur dudit rouleau chauffant (12) ; et
    ledit moyen d'amenée (41, 42, 43) amène le papier d'enregistrement lorsque les images à vireur de toutes les couleurs ont été formées sur ledit film de support d'images à vireur ;
    ce par quoi les images à vireur de toutes les couleurs sont transférées simultanément et fixées sur le papier d'enregistrement.
  15. Dispositif selon la revendication 14, comprenant de plus un dispositif de nettoyage (223) pour enlever tout vireur résiduel sur le film de support d'images à vireur après le transfert des images à vireur de toutes les couleurs sur le papier d'enregistrement, ledit dispositif de nettoyage (223) ne pouvant pas nettoyer lorsque le film de support d'images à vireur passe avec les images à vireur d'une partie seulement de toutes les couleurs.
  16. Dispositif selon la revendication 9, dans lequel ledit premier rouleau est un rouleau de pression (312) et ledit second rouleau est un rouleau chauffant (313).
  17. Dispositif selon la revendication 16, dans lequel
    ledit film de support d'images à vireur (14) est un film sans fin ;
    ledit rouleau chauffant (313) reste poussé contre ledit rouleau de pression (312) lorsque ledit film de support d'images à vireur portant l'image à vireur de chaque couleur passe entre ledit rouleau chauffant et ledit rouleau de pression ;
    des images à vireur de plusieurs couleurs sont formées successivement, étant superposées les unes aux autres, et fixées temporairement sur ledit film de support d'images à vireur ; et
    ledit moyen d'amenée (41, 42, 43) amène le papier d'enregistrement lorsque les images à vireur de toutes les couleurs ont été formées sur ledit film de support d'images à vireur ;
    ce par quoi les images à vireur de plusieurs couleurs constituant l'image en couleur sont transférées simultanément et fixées sur le papier d'enregistrement.
  18. Dispositif selon la revendication 17, comprenant de plus un dispositif de nettoyage (323a) pour enlever tout vireur résiduel sur le film de support d'images à vireur après le transfert des images à vireur de toutes les couleurs sur le papier d'enregistrement, ledit dispositif de nettoyage (323a) ne pouvant pas nettoyer lorsque le film de support d'images à vireur passe avec les images à vireur d'une partie seulement de toutes les couleurs.
  19. Dispositif selon la revendication 6, comprenant de plus un moyen (50) pour activer sélectivement les dispositifs de développement selon la couleur de l'image latente électrostatique qui est ensuite formée sur ledit élément photosensible.
EP94109201A 1989-01-27 1990-01-26 Méthode et appareil de formation d'images en couleur Expired - Lifetime EP0625732B1 (fr)

Applications Claiming Priority (9)

Application Number Priority Date Filing Date Title
JP16311/89 1989-01-27
JP1016309A JP2548792B2 (ja) 1989-01-27 1989-01-27 カラー画像形成方法
JP1016310A JP2548793B2 (ja) 1989-01-27 1989-01-27 カラー画像形成方法
JP16309/89 1989-01-27
JP1016312A JPH087483B2 (ja) 1989-01-27 1989-01-27 カラー画像形成方法
JP1016311A JPH0812501B2 (ja) 1989-01-27 1989-01-27 カラー画像形成方法
JP16310/89 1989-01-27
JP16312/89 1989-01-27
EP90101614A EP0380132B1 (fr) 1989-01-27 1990-01-26 Méthode et appareil de formation d'images en couleurs

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EP90101614A Division EP0380132B1 (fr) 1989-01-27 1990-01-26 Méthode et appareil de formation d'images en couleurs
EP90101614.7 Division 1990-01-26

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EP0625732A1 EP0625732A1 (fr) 1994-11-23
EP0625732B1 true EP0625732B1 (fr) 1997-07-30

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EP94109201A Expired - Lifetime EP0625732B1 (fr) 1989-01-27 1990-01-26 Méthode et appareil de formation d'images en couleur

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Also Published As

Publication number Publication date
DE69019179D1 (de) 1995-06-14
DE69019179T2 (de) 1996-01-25
US5057875A (en) 1991-10-15
EP0380132A3 (fr) 1992-04-15
EP0380132B1 (fr) 1995-05-10
EP0380132A2 (fr) 1990-08-01
DE69031179T2 (de) 1998-02-05
EP0625732A1 (fr) 1994-11-23
DE69031179D1 (de) 1997-09-04

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